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Battle on Big Chico Creek

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Most of us wouldn't know it by looking, but there's a war going on along the banks of Big Chico Creek. Himalayan blackberry is duking it out with California blackberry, hackberry is struggling against elderberry, and privet is vying with mugwort for biotic dominance—and that's only a tiny part of it. CSU, Chico biology professor Paul Maslin, who heads the Chico Creek Restoration Project, has become expert at recognizing the players in this battle and for many years has been working with students and citizens of the community to help the good guys win. Mugwort, elderberry, and California blackberry are some of the native plants whose habitats Maslin and crew are attempting to protect from encroachment and downright annihilation by exotic species, particularly where the creek winds through campus.

Those of us strolling the paths along the water's edge might wonder why it matters much whether a plant is native or exotic, especially given that many of the exotics seem so lush and beautiful. But it does. Native plants and animals have adapted to each other and staked out particular niches in the riparian zone. Exotic plants that thrive in the same habitat—catalpa, mulberry, silver maple—may look good but not perform the same beneficial functions. Those massive Western sycamores that lean out over the creek so languorously and soothe us on hot days with their pale peeling trunks and light green leaves are a haven for critters as well. When a branch falls off and the exposed heartwood rots, the resultant hollow makes a good home for birds and squirrels. The white alders growing by the water's edge also serve the larger creekside environment in a number of ways. Their roots fix nitrogen in the air and soil into organic forms plants can use, Maslin pointed out. "Thus alder leaves are high in protein and, when they fall into the creek, are a rich source of nitrogen supporting the food chain for animal life in the creek."

Maslin referred to the balance of flora and fauna of a given biological zone as a coherent unit developed gradually over time, often a very long time. This unit can be fairly quickly disrupted by rogue elements such as non-native plants. In a worst case scenario, an exquisitely interdependent set of relationships gives way to a monoculture. Think ivy. Think periwinkle. When these exotics gain a toehold in the shade along much of the creek, they become absolutely dominant. Said Maslin, "None of our native butterflies even use them as food." The pipevine swallowtail, a lovely gold-spotted butterfly, feeds in its larval stage "almost entirely on pipevine, which makes it toxic to its predators," Maslin continued. However, native pipevine has all but succumbed to the crush of advancing non-natives. Bottom line? "We'd have a lot more butterflies if we had a lot less ivy."

Weed killers aren't usually a part of Maslin's eradication arsenal, however. As many a student volunteer has learned to his or her dismay, at least initially, tools and stoop labor are gentle on the ecosystem even if they're not always gentle on the back. One of the trickiest plants to remove is the Himalayan blackberry, a vigorous root-sprouter. Simply chopping it out doesn't work. Every little rootlet that remains is capable of sending up a new shoot. As Maslin explained, a tined tool, heavy leather gloves, and a lot of patience is required. A good rain doesn't hurt either. Following the canes' reverse trajectory into earth, volunteers fork gingerly around them, then lift the exposed root a little at a time. It's a long process.

Another exotic most restoration workers view with dismay if not contempt is the so-called Tree of Heaven (Ailanthus). This pesky plant responds best to a process known as girdling, in which the phloem layer responsible for conveying plant sugars from the leaves down the trunk into the roots is severed. According to Maslin, "A completely girdled tree will die in one to three years, depending on the species, size, and time of girdling. In most riparian areas, dead trees do not have to be removed. In fact, they provide feeding perches for raptors and flycatchers, feeding and nesting sites for woodpeckers, and, secondarily, nest holes for titmice, tree swallows, and house finches."

Now six years old, the restoration project has become, among other things, a way for Maslin to get more people involved in the care of their ecosystem. "What are we teaching here? We're trying to say stewardship is important. I would like to see this concept of creek stewardship extended to how you manage your ranch. Ultimately, how you manage your watershed can be good for the ranch too."

Restoration is a complicated process, though, as many scientists have argued. Sometimes an environment has been so altered that it's difficult to know where and how to begin. Hence, one tool Maslin insists his students employ is the pencil. A field notebook is the restoration worker's medical chart, a place to note the health of the patient as she begins to revive. Notebooks also help students see how good record keeping can serve as "a potential guide when you take your children or students into the field." Site descriptions tend to be detailed: besides noting location, elevation, topography, and geology, they include observations about the soil and water, dominant species, types of disturbance, and what unfamiliar species are encountered.

Unfortunately, litter is often encountered too. "You'd be amazed," commented Maslin. "It's a big problem." But the process of environmental degradation is also hastened inadvertently by humans, as used to happen with the irrigation of the campus grounds along the edge of the riparian corridor. Native California plants that had adapted to long, hot summers in the Sacramento Valley, such as the valley oak (Quercus lobata), were being watered to death while forceful non-natives, such as the Tree of Heaven, were beginning to flourish. The restoration project has since convinced grounds personnel to limit irrigation, which can also more easily wash pesticides into the watershed, to areas outside the riparian zone. A small enough victory, it is nevertheless efforts like this that may ultimately keep Big Chico Creek a place frequented by such diverse organisms as giant tiger swallowtails, green herons, gray squirrels, and migrating salmon.

Over the years, said Maslin, campus policy regarding the creek seems to have gone from "total management, to leaving it alone, to 'Oh, my god, we can't leave it alone,' to landscaping naturally." Grounds personnel have embraced the project, as has the Arboretum Management Club.

"Without the club's enthusiasm and boundless optimism," he said, "the project would still be at the level of occasionally taking a pocketknife to an exotic sapling." He is also grateful to the Watershed Alliance and cites the generosity of local ranchers and nursery folk who have donated seeds and plants to the restoration project. But even with all this support, he joked about sometimes feeling "like Don Quixote, fighting something that will win in the end." Will it? Maybe. But in the meantime, campus visitors can now cross the bridge between Holt Hall and the Physical Science Building and, if they look down creek, see on the left bank an old wooden fence recently unearthed-un-ivied might be more accurate-by volunteers. Near it sprout the tender shoots of various native plants. It's encouraging to think that red admiral and satyr anglewing butterflies may soon return too.

"Restoration of Big Chico Creek's natural flora," Maslin has written, "will provide for the needs of a greater variety of native animals, increasing educational and esthetic value," and the process of restoration will also provide "both a learning laboratory for involved students and a model of ecological stewardship for our campus and our watershed."

Details of the restoration project, as well as A Management Guide for the Care of Streams, which Maslin authored with assistance from the Committee for Stewardship of Chico Creek, and a plethora of other related and fascinating links can be found at Maslin's extensive Web site: www.csuchico.edu/~pmaslin/Cr.Manag/RipRest.html.

by Beth Spencer, University Publications (Adapted from an article in Inside Chico State, September
24, 1998.)